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Square Tube Front Driveshaft for K5

C

captaininsano

1/2 ton status
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I have done a lot searching and research about this since last night both on Pirate and here. I have decided to go with the square tube front driveshaft for two reasons, strength and cost. I swapped out my th350/np203 for sm465/np205 and now I need new driveshafts, or length changed. The rear has to be done by a pro since I drive the rig to the trail, sometimes up to 300 miles.

My only question is (since I don't have my shafts handy right now) about the stock yokes on 1/2 tons. Are they cast? Some of them? None of them? I am obviously hoping none are. After reading on Pirate these seems to be confusion about this, partially about toyotas but some chevy too, hopefully the chevy experts here can clear it up about the chevy. Mine are from a 78 1/2 ton K5.

--Mark
 
Everything I've seen is "cast steel". No problems welding with common MIG/GMAW or any other method. AFAIK, that's the standard proceedure for putting all common domestic shafts together.
 
Good point, I guess my Miller should handle it then, should I pre-heat before welding it up or should I just weld a little bit at a time and keep it cool?
 
I generally just lay in a few solid tacks, followed by 25% arcs in series on opposing sides (like tightening nuts in opposing pattern). That's it. Never had a problem and I've done shafts on everything from drag raced muscle cars to my current truggy's shafts.

Word of warning on square tube shafts though. Under torque load they don't like to slip and will tend to bind, especially if you don't keep it lubed. I believe that is what cost me my last transmission when a spring gave way under load climbing a waterfall.
 
Ouch, that sucks! I did read that in another thread about this type of shaft. I have an extra set of yokes so I think I will try this out and see if I like it and if not just keep it for a spare. My buddy recommended only using this for a spare too. I kinda just want to try it out for fun anyways, not going to be fun if it shreds my drivetrain though! :doah:
 
You take a piece of 2.5" .250 wall square tube and stick a piece of 2" .250 wall square tube inside the 2.5" one. You weld the yokes on both ends of the driveshaft and you have an ultra long slip ultra strong driveshaft for cheap.

The problem is they have binding issues and if you are bound up with alot of torque on the driveshaft it might not slip when your axle is trying to move. This means the force travels up your driveline to the next weakest point. That is usually the tcase adapter or tranny.

Harley
 
my last shaft was built at the local shop and i watched it being done. thay take the ends and press it to the tube. then check for even side to side . adjust as needed and put 4 spot welds in to it. then put on the drive shaft lathe and spin at low speed and check it all . if good then thay have a big tip that holds the gun for the welder and has a remote triger and puts in in line with the joint. then sets the speed to the proper speed and holds the trigger till its 360 welded no preheat or any thing. just wanted to pass this on to you.


and this is the same lathe that balences the shaft just like a tire balencer does.
 
Hossbaby50 said:
You take a piece of 2.5" .250 wall square tube and stick a piece of 2" .250 wall square tube inside the 2.5" one. You weld the yokes on both ends of the driveshaft and you have an ultra long slip ultra strong driveshaft for cheap.

The problem is they have binding issues and if you are bound up with alot of torque on the driveshaft it might not slip when your axle is trying to move. This means the force travels up your driveline to the next weakest point. That is usually the tcase adapter or tranny.

Harley
Click to expand...


Thank you, got it now! :)
 
dang :thumb: I want one... fully extended you can see the splines in my shaft... I just know it's going to give out some time soon..
 
Finished mine last night, took about 3 hours all in all. I am pretty happy with the outcome, just need to measure and cut the tubes to the proper length and install it. :grin: I put the larger tube on the bottom, thinkin that the lip of the bigger tube going in an upward direction has less chance of catching on a rock, might fill up with crap though, I will probably drill some small holes at the bottom to allow any water that might get in there drain out. Going to round the leading edge of the small tube once it is cut also to hopefully reduce the chance of binding. We figured the math last night and I think we came up with 14 inches of travel, definitely over kill.

16843Finished_Yoke.JPG


16843Finished_Product.JPG


168432inchTube_Double_Cardan.JPG
 
i have a idea. cap off the end of the inner tube and then drill hole and put grease fitting in the outer tube and it will grease like a regulare shaft and slide much easyer. but when greaseing it make sure it is at full stuff so no extra grease is in the end to come out in a hurry at next full stuff.
 
I would run the larger tube up top with the smaller end conneceted to the pinion. This way if you get water in the driveshaft is can drain out. Or drill a drain hole in your lower larger tube.

If you fill it with water and it can't drain bad things will happen when you try and compress it.

As for greasing I would drill 4 holes one in each side and install 1 zerk per side to be able to completely grease the shaft on all sides. I would situate the holes relatively close to the end of the 2.5" tube.

Be very careful if you build one of these for a rear shaft. They are more prone to the common failure type. I would also try and polish up the inner 2" tube to help it slip better.

Harley
 
ALready welded mine up for large tube on bottom, , not too worried about the water, I am going to drill some holes for drain, and grease the hell out of it, should be fine.

The rear is going to be normal round I guess, I have to drive the rig to trails still :( I do have a long shaft from a pickup that I think I will shorten and have balanced. Might just have South Bay Driveline do the shortening too to save me the hassle and make sure it is straight.

Wonder if they can balance the front square one? :D j/k
 
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